Uncertainty: a Crucial Part of Perceivable Reality
      Historical evidence shows that time and again entire societies had false ideas about reality. For example, people believed in sun gods, rain gods and other gods. Centuries later, when the actual, physical causes of the sun, rain, and other phenomena were understood, the gods were seen to be creations of human imaginations. For many centuries people also believed that the sun and other heavenly bodies moved around Earth and that earth, air, fire, and water were the ingredients of all things. These false beliefs were due to misleading evidence as well as people's imaginations.

      Even in the 20th century intelligent people had false ideas that did not agree with verifiable evidence and objective reasoning. For example, the influential philosopher, John Dewey, wrote as follows in the first four sentences of Chapter I of his book, Reconstruction in Philosophy (Beacon Press, 1948). "Man differs from the lower animals because he preserves his past experiences. What happened in the past is lived again in memory. About what goes on today hangs a cloud of thoughts concerning similar things undergone in bygone days. With the animals, an experience perishes as it happens, and each new doing or suffering stands alone." Obviously Dewey had little experience with other animals, or he was a poor observer, or he was unaware of the widespread evidence showing that the animals of many other species have excellent memories of what happened in the past and that their memories influence how they think and behave in their current circumstances. Possibly Dewey was taught his incorrect view of animal memory and never questioned it because it made sense in his overall perception of reality.

      Conclusive evidence shows that we go through life with false ideas about subjects as important as the sun, the composition of the matter in our bodies and environments, the causes of our beliefs, and the intelligence of other animals. In the past, false ideas about the causes of diseases and other complex subjects were the rule rather than the exception. This evidence and objective reasoning leads us to the following observable fact on which Perceivable Reality is based. Believing something is true does not make the belief true. We can also make the following related assertion. Every belief or perception has an associated probability of being true, and the probability depends on an objective assessment of all the related evidence. For example, large amounts of corroborating evidence permit us to assign a probability near 100% to the view that many kinds of dinosaurs once roamed Earth. And evidence about flying saucer sightings and people's dreams, imaginations, and causes of false recollections allow us to assign a probability near 0% to the view that aliens from another world visited earth and gave people flying saucer rides.

     Perceivable Reality includes every currently existing alternative view and its probability of being consistent with Ultimate Reality. The probabilities reflecting the uncertainties of the views are crucial to the accuracy and effectiveness of Perceivable Reality. It is the lack of realistic probabilities and reasons for each probability that causes people's overconfidence in unrealistic perceptions, which causes irresolvable disagreements among people.